The Ford Explorer is a range of SUVs manufactured by Ford Motor Company since the 1991 model year. The first four-door SUV produced by Ford, the Explorer was introduced as a replacement for the two-door Bronco II. Within the current Ford light truck range, the Explorer is slotted between the Ford Edge and Ford Expedition. As with the Ford Ranger, the Explorer derives its name from a trim package previously offered on the Ford F-Series pickup trucks. Currently in its sixth generation, the Explorer has been offered with multiple chassis and powertrain layouts. The first two generations were directly derived from the Ford Ranger, switching to a model-specific chassis for the third and fourth generations. The fifth generation was repackaged as a CUV, adopting a variant of the Ford Taurus chassis architecture (developed for SUV use). Alongside the five-door Explorer wagon, a three-door Explorer wagon was offered from 1991 to 2003, serving as the direct replacement of the Bronco II; the 2001-2010 Ford Explorer Sport Trac was a crew-cab pickup derived from the model line. For police use, the Ford Police Interceptor Utility has been derived from the fifth and sixth-generation Explorer to replace Ford Crown Victoria Police Interceptor (and the later Taurus-based Police Interceptor Sedan). Through rebranding, Mazda, Mercury, and Lincoln have sold versions of the Explorer; Lincoln currently markets the sixth-generation model line as the Lincoln Aviator. The first four generations of the Explorer were produced by Ford at its Louisville Assembly Plant (Louisville, Kentucky) and at its now-closed St. Louis Assembly Plant (Hazelwood, Missouri); the model line is now currently produced at Chicago Assembly (Chicago, Illinois).